Start Mashed Potatoes: Wash and peel potatoes. Cut into 1-2 inch cubes, submerge in cold water and bring to a boil.

Start Filling: Preheat oil in a large pan over medium-high heat. Add the diced onions, celery, and frozen veggies. Saute for 3 minutes. Add the garlic and cook for 1 minute.

Make Gravy: Add the chicken broth, beef broth, beef bouillon, onion and garlic powder, and Worcestershire sauce to a medium saucepan. Stir to combine. Optional: If a darker color is desired, add 2-3 drops of Kitchen Bouquet browning and seasoning sauce. (Gravy Master works well too.) Bring gravy to a boil.

Combine the cold water and cornstarch in a small Tupperware with a lid. Shake to combine. Whisk in cornstarch mixture. Allow gravy to thicken, then decrease to medium-low. Let it gently simmer for 2-3 minutes, or until your desired thickness and concentration is obtained. Set aside.

In Filling Pan: Increase heat to high. Add the ground beef. Cook and crumbled until cooked through. Drain all excess grease.

Once potatoes are fork tender, drain and add to stand mixer with cream, butter and salt. Beat until light and fluffy. Set aside.

In Filling Pan: Reduce heat to medium-high. Sprinkle in the flour and toss to coat. Add the Tomato Paste and thyme. Cook for 1-2 minutes.

Deglaze the pan with the Chicken broth. Use a silicone spatula to scrape up any brown bits from the pan, this adds flavor to the filling.

Add the brown gravy.

Season with salt/pepper. Taste and adjust seasoning as needed. Remove from heat.

Transfer to a lightly greased 9-inch pie pan or 7 x 11 casserole dish. Carefully spread warm mashed potatoes on top.

Use a fork to “rake” lines into the mashed potatoes.

Set the oven rack about 5 inches away from the broiler. Set to a high broil, 550 degrees.

Broil for about 5 minutes watch it after 2 minutes, it will go from perfectly browned to burned quickly.

Remove from heat and serve.